Hello,
syzbot found the following issue on:
HEAD commit: 0a805b6ea8cd Linux 6.6.116
git tree: linux-6.6.y
console output:
https://syzkaller.appspot.com/x/log.txt?x=11d238b4580000
kernel config:
https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link:
https://syzkaller.appspot.com/bug?extid=cb6f25516cd712ca5054
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image:
https://storage.googleapis.com/syzbot-assets/13874446b4b2/disk-0a805b6e.raw.xz
vmlinux:
https://storage.googleapis.com/syzbot-assets/69a5e59e1ade/vmlinux-0a805b6e.xz
kernel image:
https://storage.googleapis.com/syzbot-assets/322c0711f976/bzImage-0a805b6e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by:
syzbot+cb6f25...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-out-of-bounds in copy_to_urb+0x255/0x440 sound/usb/pcm.c:1437
Write of size 264 at addr ffff8880685fab00 by task syz.2.2522/18536
CPU: 0 PID: 18536 Comm: syz.2.2522 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x220 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
__asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
copy_to_urb+0x255/0x440 sound/usb/pcm.c:1437
prepare_playback_urb+0x932/0x1360 sound/usb/pcm.c:1565
prepare_outbound_urb+0x372/0xc40 sound/usb/endpoint.c:336
snd_usb_endpoint_start+0x4d9/0x1440 sound/usb/endpoint.c:1618
start_endpoints+0xa1/0x270 sound/usb/pcm.c:273
snd_usb_substream_playback_trigger+0x3e0/0x7a0 sound/usb/pcm.c:1669
snd_pcm_do_start+0xb1/0x170 sound/core/pcm_native.c:1443
snd_pcm_action_single sound/core/pcm_native.c:1293 [inline]
snd_pcm_action+0xda/0x230 sound/core/pcm_native.c:1376
__snd_pcm_lib_xfer+0x16fa/0x1c40 sound/core/pcm_lib.c:2341
snd_pcm_oss_write3+0x1bc/0x320 sound/core/oss/pcm_oss.c:1252
snd_pcm_plug_write_transfer+0x2b8/0x4a0 sound/core/oss/pcm_plugin.c:630
snd_pcm_oss_write2 sound/core/oss/pcm_oss.c:1384 [inline]
snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1450 [inline]
snd_pcm_oss_write+0xbb5/0x1120 sound/core/oss/pcm_oss.c:2810
vfs_write+0x288/0x940 fs/read_write.c:582
ksys_write+0x147/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f597638f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5977284038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f59765e5fa0 RCX: 00007f597638f749
RDX: 00000000000005ce RSI: 0000200000000640 RDI: 0000000000000004
RBP: 00007f5976413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f59765e6038 R14: 00007f59765e5fa0 R15: 00007ffec690ca08
</TASK>
Allocated by task 18536:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1007 [inline]
__kmalloc+0xb4/0x240 mm/slab_common.c:1020
data_ep_set_params sound/usb/endpoint.c:1263 [inline]
snd_usb_endpoint_set_params+0x1575/0x28e0 sound/usb/endpoint.c:1395
snd_usb_hw_params+0x123e/0x19c0 sound/usb/pcm.c:569
snd_pcm_hw_params+0x835/0x1c50 sound/core/pcm_native.c:779
snd_pcm_oss_change_params_locked+0x2144/0x3d30 sound/core/oss/pcm_oss.c:976
snd_pcm_oss_make_ready_locked sound/core/oss/pcm_oss.c:1197 [inline]
snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1415 [inline]
snd_pcm_oss_write+0x2ff/0x1120 sound/core/oss/pcm_oss.c:2810
vfs_write+0x288/0x940 fs/read_write.c:582
ksys_write+0x147/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:45
__kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
kvfree_call_rcu+0xee/0x780 kernel/rcu/tree.c:3452
kernfs_unlink_open_file+0x414/0x4c0 fs/kernfs/file.c:653
kernfs_fop_release+0x12e/0x190 fs/kernfs/file.c:825
__fput+0x234/0x970 fs/file_table.c:384
__do_sys_close fs/open.c:1571 [inline]
__se_sys_close+0x15f/0x220 fs/open.c:1556
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Second to last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:45
__kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
kvfree_call_rcu+0xee/0x780 kernel/rcu/tree.c:3452
kernfs_unlink_open_file+0x414/0x4c0 fs/kernfs/file.c:653
kernfs_fop_release+0x12e/0x190 fs/kernfs/file.c:825
__fput+0x234/0x970 fs/file_table.c:384
__do_sys_close fs/open.c:1571 [inline]
__se_sys_close+0x15f/0x220 fs/open.c:1556
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff8880685fab00
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of
allocated 120-byte region [ffff8880685fab00, ffff8880685fab78)
The buggy address belongs to the physical page:
page:ffffea0001a17e80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x685fa
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff8880178418c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 6255, tgid 6255 (udevd), ts 581364066957, free_ts 581148136550
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
alloc_slab_page+0x5d/0x170 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2e0 mm/slub.c:2081
___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
__kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
kernfs_get_open_node fs/kernfs/file.c:592 [inline]
kernfs_fop_open+0x7d7/0xcc0 fs/kernfs/file.c:760
do_dentry_open+0x8c6/0x1500 fs/open.c:929
do_open fs/namei.c:3640 [inline]
path_openat+0x274b/0x3190 fs/namei.c:3797
do_filp_open+0x1c5/0x3d0 fs/namei.c:3824
do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
do_sys_open fs/open.c:1434 [inline]
__do_sys_openat fs/open.c:1450 [inline]
__se_sys_openat fs/open.c:1445 [inline]
__x64_sys_openat+0x139/0x160 fs/open.c:1445
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
release_pages+0x1fa0/0x2220 mm/swap.c:1022
tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
tlb_flush_mmu+0x368/0x4f0 mm/mmu_gather.c:300
tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:392
exit_mmap+0x3f0/0xb50 mm/mmap.c:3315
__mmput+0x118/0x3c0 kernel/fork.c:1355
exit_mm+0x1da/0x2c0 kernel/exit.c:569
do_exit+0x88e/0x23c0 kernel/exit.c:870
do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
get_signal+0x12fc/0x1400 kernel/signal.c:2902
arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
Memory state around the buggy address:
ffff8880685faa00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880685faa80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880685fab00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
^
ffff8880685fab80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880685fac00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
==================================================================
---
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